Density, snow, and seasonality lead to variation in muskox (Ovibos moschatus) habitat selection during summer

Abstract

Understanding how environmental conditions influence habitat selection and suitability of free-ranging animals is critical, as the outcome may have implications for individual fitness and population dynamics. Density and snow are among the most influential environmental conditions driving habitat-selection patterns of northern ungulates. We used two decades of census data from high Arctic Greenland to quantify inter- and intra-annual variations in muskox (Ovibos moschatus (Zimmermann, 1780)) habitat selection and suitability during the Arctic summer (July through October). Across years, habitat selection varied considerably, and the strength of habitat selection appeared negatively related to both muskox density and spring snow cover. In early summer, habitat suitability was high and spatially rather uniform. Towards the autumn, suitable habitats contracted to just the lower elevations, when muskoxen exhibited increasingly stronger habitat selection towards low elevations and dense vegetation. This selection strategy clearly reflects the need to build up fat reserves for the upcoming winter, highlighting the energetic importance of the Arctic summer. Extreme climatic events such as freezing rain in autumn are increasing in frequency in Greenland and limit muskox access to high-quality forage in fens. Such events may therefore negatively affect the energy acquisition process of muskox with potential cascading consequences on population dynamics.